One method of controlling combustion in a conventional internal combustion engine is with spark-ignition leading to flame propagation, referred to homogeneous-charge spark-ignition (SI). It is well known in conventional homogeneous-charge spark-ignition (SI) engines that cyclic variability of the ignition process is strongly affected by in-cylinder charge motion during spark discharge. For example, it has been demonstrated that better ignition characteristics resulted by convecting an early flame-kernel away from each spark electrode to minimize spark energy loss. In particular, in-cylinder charge motion, e.g., swirl and tumble components, in conjunction with combustion chamber design have been used to manipulate a spark-discharge plasma channel away from the spark-plug electrodes. This action improves ignitability of both stoichiometric and dilute air/fuel mixtures in both homogeneous-charge and stratified-charge spark-ignition gasoline engines.
The importance of using spark-ignition for combustion phasing control in direct-injection controlled auto-ignition combustion engines has also been demonstrated. Use of spark-ignition to control combustion phasing in a direct-injection gasoline auto-ignition combustion engine operating at light load and idle, and to enable cold start using a conventional compression ratio has been described in U.S. Pat. No. 6,971,365 B1, entitled AUTO-IGNITION GASOLINE ENGINE COMBUSTION CHAMBER AND METHOD, issued to Najt, et al., on Dec. 6, 2005. Use of fuel injection and spark-ignition strategies to extend the mid-load operation limit of a gasoline direct-injection controlled auto-ignition combustion engine has been described in U.S. Pat. No. 6,994,072 B2, entitled METHOD FOR MID LOAD OPERATION OF AUTO-IGNITION COMBUSTION, issued to Kuo, et al., on Feb. 7, 2006. There are many geometrically constrained design limitations for optimal engine operation which affect the ability of the spark-discharge plasma channel to be located at an ignitable region of the fuel-air mixture; these included relative position between the spark plug, the fuel injector, combustion-chamber geometry, and piston-bowl geometry.
There is a need for a powertrain control system, comprising either a homogeneous- or stratified-charge, controlled auto-ignition internal combustion engine, wherein ignition of a combustible charge in a combustion chamber is controlled.